EDecimal

The value written out in the decimal precision of the moment it is asked for,
not of the moment the rational was made: an integer's exact form is the
ERational, and writing a hundred digits out for every integer
and fraction the simplifier makes was a third of the cost of making one
(https://github.com/asc-community/AngouriMath/issues/1338). Kept with the
context it was written in and written again in another: kept alone, a
rational first asked at the default precision answered a hundred digits
under a context of three hundred, and so did every value computed from it
(https://github.com/asc-community/AngouriMath/issues/1868).